The disclosure relates to an ultrasound-based measuring device and also to an ultrasound-based measuring method.
The use of ultrasound for determining the length e.g. of a solid body is known in practice for a multitude of issues, such as, for instance, in the field of nondestructive material testing. In many cases the so-called pulse echo method is used here, in which the length of a measurement body is deduced from the propagation time between emission of an ultrasonic pulse into the measurement body and reception of the pulse echo reflected e.g. at the rear wall of said measurement body.
For this purpose, a precision time base is required as reference for the time measurement, wherein in practice quartz-crystal oscillators are principally used in this regard. Moreover, the sound speed in the body to be examined has to be known, or has to be determined by a reference measurement on a body of known length and of the same material.
In all propagation-time-based distance measurements the temperature response is problematic, however, since it can exceed the effect actually to be measured by a multiple, as a result of which the measurement variable can occasionally be corrupted to the extent of being unusable.
Therefore, in many applications, the temperature of the measurement body has to be determined accurately to a tenth or hundredth of a degree. Guaranteeing this measurement accuracy in the context of unavoidable fluctuations of manufacturing parameters over the entire service life of a temperature measuring device is practically impossible or possible only with untenable costs.
Against this background, it is an object of the present disclosure to develop a generic measuring device and a generic measuring method to the effect that a length measurement independent of temperature-dictated measurement section or propagation time changes in the ultrasonic signals is made possible in a simple and cost-effective manner.